To be safe, remember to plug or cap the outlets of propane cylinders before moving them
Sounds like a good idea to keep the valve clean, but the little caps that come with the bottles sure would not stop a leak. And I recently learned those caps and plugs can be hard to find if you'd like to buy one.
all tanks have to be upright
Of course that's the safest thing, but even 100# bottles have frequently been transported horizontally with no problems as long as everything is intact, they don't get damaged, and they're set upright before using them.
How long has it been since you've seen oxygen and acetylene tanks transported horizontally? From 1945 to 1950, my dad drove a flat bed truck selling and delivering welding supplies in south central Oklahoma. All the oxygen and acetylene tanks were stacked like cordwood and held on with chains and chain booms. Of course they had the caps to protect the valves. Tailgate lifts didn't exist, and no two wheel dollies were used, so he had a knack for grabbing the cap on the top and spinning the bottles to "roll" them along. At the truck, he'd grab the top, pull it toward himself at the same time he put his knee into the middle of the bottle and flipped it up onto the truck, bottom first.
He could walk in and out of the shops spinning a bottle in each hand, but said he never got the knack of doing a third bottle in the crook of one elbow like the guys at the National Cylinder Gas plant in Oklahoma City where they unloaded his empties and reloaded the truck with full bottles once a week.
OSHA would have a fit if they saw that today.
